Mesoparasitic copepods (Copepoda: Cyclopoida) associated with polychaete worms in European seas Boxshall, Geoff A. O’Reilly, Myles Sikorski, Andrey Summerfield, Rebecca Zootaxa 2019 2019-04-09 4579 1 1 69 Heegaard, 1942 Heegaard 1942 [288,615,1704,1730] Polychaeta Sabellidae Chone GBIF Animalia Sabellida 29 30 Annelida species eteonicola   Material examined: 1 ovigerous ♀from  Eteone spetsbergensisMalmgren, 1865, 3697 Svalbard, Adventfjorden, Stn 5-4 ( 78° 13’00”N, 15° 13’00”E), depth 30-60 m, 0 8 September 2011; collected by A. Sikorski; NHMUK Reg. No. 2016.520.   Differential diagnosis.Adult female body comprising ectosoma connected to endosoma via short stalk. Ectosoma of mature female 2.1 times longer than maximum width (length 0.93 mm, maximum width 0.44 mm); tapering posteriorly. Ectosoma bearing antennules, antennae and maxillipeds typical for genus; lacking any vestige of trunk limbs and caudal rami. Anus lacking. Genital apertures paired, located anteriorly on underside of ectosoma. Egg sacs 4.55 mmlong: egg arrangement multiseriate with about 5 longitudinal rows visible in any view ( Fig. 12); eggs spherical, mean diameter 92 µm(range 84 to 104 µm). Stalk short and broad, connecting to endosoma within host. Endosoma comprising 2 elongate rootlets penetrating body cavity of host.   Remarks. Heegaard (1942)based his original description on two females found on  Eteone longacollected in sand on an island beach outside Trondheim fjord (western Norway). It was subsequently reported from the east coast of North America by Lützen (1964b)on  E. longa. The female recorded here was collected from  Eteone spetsbergensis, a new host, and it was attached in the mid-body region of its host ( Fig. 10). Cyclorhiza eteonicolawas reported from UKwaters by O’Reilly & Geddes (2000), who found 5 non-ovigerous females on  E. longanear Holy Island, off the coast of Northumberland. However, O’Reilly (2000)subsequently concluded that this material could equally be attributed to  C. megalovasince egg size is diagnostic and these specimens were non-ovigerous.